Derangements in lung vascular permeability, particularly in the context of acute lung injury (ALI), represent a common yet difficult clinical problem clearly associated with increased morbidity and mortality and effective therapies for the vascular leak associated with ALI are currently not available. The statins, a class of HMG CoA-reductase inhibitor, are used clinically for their ability to lower serum lipid levels and reduce the morbidity and mortality associated with coronary artery disease. However, not all of their beneficial effects can be attributed to cholesterol lowering. Accordingly, we have hypothesized that via complex effects on endothelial cells (EC), simvastatin induces barrier protection and offers a novel therapeutic strategy for acute lung injury (ALI) and ventilator-associated lung injury (VALI). In support of our hypothesis, we recently reported that simvastatin promotes endothelial cell (EC) barrier function in vitro in the presence of edemagenic agonists, a finding with dramatic significance with respect to clinical conditions characterized specifically by increased vascular permeability such as ALI/VALI. The underlying mechanism by which simvastatin augments EC barrier function, however, remains unclear and is the subject of this K08 application. We have identified a dual EC simvastatin response characterized by distinct early and delayed effects. We now propose to enlist a highly translational, mechanistic approach to further investigate simvastatin effects on EC. In Specific Aim 1, we will characterize simvastatin modulation of EC responses to thrombin and TNF-a, clinically relevant agonists, and to cyclic stretch, relevant to VALI. In Specific Aim 2, we will explore the temporal (early) EC simvastatin response with respect to the functional role of cortactin, an actin-binding protein which translocates peripherally within 2 h of simvastatin treatment. In Specific Aim 3, we will examine the temporal (delayed) effects of simvastatin on differential EC gene expression employing microarray analysis of human and mouse lung microvascular EC with specific focus on gene ontologies including cytoskeletal components and regulators. Finally, in Specific Aim 4, we will use a well-developed mouse model to investigate the potential therapeutic role of simvastatin in ALI/VALI. Our proposed studies will further the current understanding of statin effects on the endothelium and may have profound clinical relevance.